Lithops. Stone plants. Living stones. Flowering stones. Brains. Each one unique. They are one of the most fascinating succulents, and anyone who sees one reacts differently.
My journey with lithops started with a few given to me about two years ago. Thinking I could treat them as I did any standard succulent, I started out with supreme confidence. If there is one thing this plant will do, it is to humble you. Given that I live in an area about as far removed in climate from their natural habitat, that was pretty much always going to happen.
At that point I decided I needed to educate myself.
Lithops are small mimicry plants which are made up of two leaves which are fused together. These leaves are semi-translucent and the flattened top part operates as a window and is the means by which the plant receives the light it needs. They are found in areas of Southern Africa which are extremely dry and receive minimal rainfall. As a result of this, their capacity to store water is immense. They also sit close to the ground to protect them from the heat.
Annual Cycle of Lithops
Lithops follow a very distinct annual cycle, and it is this which is the most important to understand. Having said this, different species do follow slightly different timelines.
By spring, the new leaves should be established, and the old leaves should be totally dry. The new leaves continue to grow and become established during this time.
In summer they become dormant. In their natural habitat this ensures they survive the hottest and driest time of the year. They require little to no water at this time and any water they receive will cause them to rot.
In autumn, they start to grow. The groove between the leaves will open up and a bud will emerge. In each case a single flower will appear. The flowers open during the afternoon and are mostly yellow and white. Lithops will only flower when they are between 3 and 5 years old. In nature, lithops will start flowering after the seasonal rains start, so the beginning of autumn is the time to start watering.
During winter, the plant continues to grow. At this time, the leaves will separate and start to shrivel, with new leaves growing from between the old leaves. The new leaves receive all their moisture and nutrients from the old leaves. In some cases, more than one set of new leaves will appear, and in this way lithops may form clumps. The leaves continue to dry until they are thin and papery. At this point, they can be removed.
Watering through the seasons
It is very important to understand this life cycle and to ensure watering is appropriate to each stage. In my experience, this is where things go wrong with these plants.
In summer, when the plants are dormant, do not water at all. If they shrivel badly, a small amount of surface water can be given to them, but only until they plump up again.
The end of summer is the time to start watering. It is always best to water deeply, as lithops have long taproots which do not receive surface moisture. It is important to allow the substrate to dry out completely between watering. After flowering, watering should be steadily reduced. By the end of autumn, watering should be stopped to allow the plants to prepare for winter.
While the old leaves are shrivelling and the new leaves are appearing, it is important to not water the lithops. They derive all their moisture and nutrients from the old leaves and it is important that this process is allowed to happen. Watering at this stage will halt the absorption of the old leaves and inhibit the development of the new leaves.
Once the old leaves have dried out, watering can be gradually increased. In mid spring some deep watering is called for, once again letting the soil dry out properly between watering.
As it warms up and summer approaches, reduce watering.
For me, there are two critical issues to growing lithops.
The first is to understand the watering patterns and to work out how best to fit these into my own conditions. I live in an area with high summer humidity. In fact, we probably have higher levels of humidity all year round than lithops would find naturally. I have to work around this in working out how much to water. Summer is especially tricky as they do not want any water at this time and the environmental humidity can be significant.
Growing medium or Substrate
The second consideration is choice of substrate. I started with far too much organic matter in my substrate and I lost a fair number of lithops to rot. This soil just did not dry out fast enough and lithops left sitting in moisture are prone to rot. I then started adding pool filter sand into my mix and this helped, but still wasn’t sufficient. I have now started using pumice, which is widely recommended for lithops and other succulents. I prepare a mix with 90/10 proportions. The 90% is made up of pumice and some filter sand. This mix allows me to provide different consistencies in the substrate. The 10% is made up of soil. The health of my lithops has shown a significant improvement since making the change and I face summer a little less afraid than I have previously.
These little plants can be frustrating and at times soul destroying. But when you get it right and are able to watch the leaf changes and the flowers appear, they are by far and away the most exhilarating plant to own.